Multi-plasmon absorption in graphene

摘要: We show that graphene possesses a strong nonlinear optical response in the form of multi-plasmon absorption, with exciting implications classical and quantum optics. Specifically, we predict nano-ribbons can be used as saturable absorbers low saturation intensity far-infrared terahertz spectrum. Moreover, two-plasmon absorption extreme localization plasmon fields nano-disks lead to blockade effect, which single quantized strongly suppresses possibility second plasmon. The field optics ranges from fundamental questions concerning light-matter interactions technological applications [1]. However, usually very large intensities are required observe effects. One is thus always looking for systems will exhibit phenomena at lower powers, ultimate limit being between just two quanta light [2]. increase effects use enhancement electromagnetic surface excitations [3]. In regards, note [4] has been demonstrated support extremely localized plasmons [5–12]. While nonlinearities have studied by several authors [13–24], here novel effect absorption. also how this leads input powers such twoplasmon it becomes nearly impossible excite system. This would cause nano-disk behave essentially like two-level system, observable its resonance fluorescence Graphene two-dimensional hexagonal lattice carbon atoms [4]. low-energy band structure described Dirac cones electron dispersion Enk = n~vF|k|, where vF 10 6 m/s, n ±1 stands conduction (valence) [25]. intrinsic zero-gap semiconductor; however, easily doped free carriers supports modes [5–7]. At frequencies, one get rather accurate description these using simple Drude conductivity, �(!) e 2 EF �~ i ! +i ,